Original research
Brief in-play cooling breaks reduce thermal strain during football in hot conditions

https://doi.org/10.1016/j.jsams.2019.04.009Get rights and content

Abstract

Objectives

The study examined if three feasible strategies involving additional in-play cooling periods attenuate the core (rectal) temperature rise during simulated football matches.

Design

Four counterbalanced experimental trials in an environmental chamber set to 35 °C ambient temperature, 55% relative humidity, and 30 °C WBGT.

Methods

Twelve healthy well-trained football players completed a regular simulated match (REG), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption (COOLwater), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption and the application of an ice towel around the neck (COOLtowel), regular simulated match with an extended (+5 min; total of 20-min) half-time break (HTextended).

Results

The difference in rectal temperature change was significantly lower in the COOLwater (−0.25 °C), COOLtowel (−0.28 °C), and HTextended (−0.21 °C) trials in comparison to the REG (all p < 0.05). Exercising heart rate and session rating of perceived exertion was lower in the COOLwater (−13 bpm; −1.4 au), COOLtowel (−10 bpm; −1.3 au), and HTextended (−8 bpm; −0.9 au) trials in comparison to the REG trial (all p < 0.05). The cooling interventions did not significantly change skin temperature or thermal sensation in comparison to the REG (all p > 0.05).

Conclusions

All three cooling interventions attenuated core body thermal strain during simulated matches. The laboratory-based study supports the use of brief in-play cooling periods as a means to attenuate the rise in core temperature during matches in hot and humid conditions.

Section snippets

Practical implications

  • The efficacy of currently advocated brief in-play cooling breaks are supported by this laboratory-based study.

  • The COOLwater and HTextended strategies appear more feasible for all levels of play than COOLtowel whilst providing similar cooling benefits.

  • The HTextended strategy may be preferred by organisations that do not desire breaks during each half of play and allows further time for additional and more extensive cooling strategies during half-time.

Methods

Twelve healthy well-trained football players were recruited, provided written informed consent to participate, and completed the study. The mean age, height, body mass, and maximal oxygen consumption was 24 ± 7 y, 179 ± 5 cm, 75 ± 6 kg, and 58 ± 3 mL/kg/min, respectively. Additionally, five other participants withdrew from the research due to illness and injuries sustained during football participation external to the study. The study had institutional ethics approval.

Participants completed one

Results

Resting USG was similar among the REG (1.011 [1.007–1.015]), COOLwater (1.013 [1.007–1.019]), COOLtowel (1.014 [1.008–1.019), and HTextended (1.009 [1.004–1.013]) trials (p = 0.308). The mean trial environmental conditions were 35.7 (35.6–35.8) °C ambient temperature, 52.5 (52–53.1)% relative humidity, and 30.1 (30.1–30.2) °C WBGT.

The mean difference in Trec change between rest and the 30-min mark for each trial was similar (p = 0.377; Fig. 2). There was a main effect of session between the 30

Discussion

In support of our hypothesis, the COOLwater, COOLtowel, and HTextended trials attenuated thermal (Trec) strain in comparison to a REG trial. Neither intervention resulted in a significantly greater cooling effect upon core body temperature than the others. The brief cooling interventions also reduced markers of exercise intensity (HR and sRPE) but did not significantly influence mean skin temperature or thermal sensation.

This is the first study to examine the effect of advocated brief in-play

Conclusion

The current laboratory-based controlled study supports the use of brief in-play cooling periods, as currently advocated by FIFA and other football organisations, as a means to attenuate the rise in core body temperature during matches in hot and humid conditions. The implementation of the cooling interventions are considered feasible in a low-cost community setting, especially the COOLwater and HTextended strategies.

Acknowledgments

This research was supported by funding provided by Western Sydney University (Australia). The authors would like to thank the participants that volunteered for the study.

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